Sanding machine



C- 1931. R. A. PONSELLE SANDING MACHINE Filed June 28, 1927 2Sheets-Sheet l INVENT 6M4. M2 161 g JZ m,M Z 7 ATTORNEYS Dec. 8, 1931.R. A. PONSELLE SANDING MACHINE Filed June 28, 1927 ATTORNEYS 2Sheets-Sheet 2 Patented Dec. 8, 1931 PATENT OFFICE ROBERT A. PoNsELLE,on NEW YORK, N. Y.

SANDING MACHINE 1 Application filed June 28, 1927. Serial No. 202,021.

This invention relates to sc -called sanding machines used for woodworking purposes and is concerned more particularly with an abrasivetool or element used in sue a machine to perform the actual work. Thistool is mounted on the machine to be rotated .at a suitable rate ofspeed and has an abrasive surface which contacts with the article to beoperated on.

The tools employedfin machines of the kind referred to ordinarilyinclude a support which is 0 eratively connected to a driven shaft, andt e abrasive surface takes the form of a disc of abrasive sheet materialremovmovably secured to the support. As" these discs become worn andlose their abrasive qualities in service, more or less frequentreplacement is required, dependin on the character of the material beingwoi' ked, and the operation being performed.

The object of the present invention is to provide a sanding machinewhich includes a readily removable abrasive tool, this tool being soarranged and constructed that replacement of the worn abrasive disc iseasily and rapidly accomplished. The new tool further includes areliable clampin means for holding the disc in position w ile the toolis in use and also a locking device for locking the clamping means aalnst releasing the disc during use. This lbcking device 1s brought intoaction and is eflective only when the tool is mounted in operativeposition in the machine, and accordingly, 1t 1n no way interferes withthe release of the clamping means under those conditions that wouldprevail when such release is intentional and replacement of a disc is tobe made. So long as the tool is in operative osition, however, theclamping means is loc ed and the disc is held firmly so that tearing orother injury to it is avoided. v

The new tool is of especial utility in a portable sanding machine to beused for treating wood floors andt-hat adaptation of on upper and lowerball bearin 17, 18, on a stud shaft 19 extending through 5 the inventionwill be described merelyfor purposes of illustration. In one suchmachine the tool or element is mounted on the end of a vertical drivenshaft, and the face of the tool covered with the abrasive disc lies incontact with the floor, the entire weight of the machine pressing thecutting surface against the floor.

The construction of a sanding machine for treating floors is illustratedin the accompanying drawings, in which,

Fig. 1 is a view of a convenient form of the sanding machine in sideelevation with certain parts shownin vertical section on the line 11 ofFig. 2,

Fig. 2 is a transverse sectional view on the line 2-2 of Fig. 3,

Fig. 3 is a view in side elevation showing the driving connections andthe tool detached from the remainder of the machine,

Fig. 4 is a transverse section on the line 4-4 of Fig. 1, O

Fig. 5 is a vertical section on the line 55 of Fig. 4, Y

Fig. 6 is a sectional view of a detail, and

Fig. 7 is a face view of the abrasive disc.

' While the present tool is suitable for use with various types ofmachines to be used for different purposes, it is here illustrated inthe form most suitable for use in a sanding machine for operating onfloors. This machine includes a base or frame 10 on which is mounted anelectric motor 11 having a driving shaft 12 which drives a chain 13through suitable gearing and a vertical shaft mounted within a housing14. The chain drives a sprocket wheel 15 mounted on the upper end of atubular hub 16 which is in turn mounted assemblies a boss 20 in theframe and having a nut 21 at its upperv threaded end 22 b which the studshaft is held in position. T e ball hear, ing assemblies are mounted inposition with a driving fit and are held separated v,

; ill

than the diameter of the felt ring bular spacer 23. A cap plate 24, heldin lace by screws on the lower end of the stud s aft, assists in holdingthe inner race of the lower assembly 18 in position, and a cap mountedon the lower end 0f the hub 16 by screws, serves to close the end of thehub and also supports the outer race of the lower bearing assembly. Aring plate 26 secured to the upper face of the sprocket wheel overliesthe upper end of the tubular hub so as to prevent ghei) entrance of dirtinto the interior of the Mounted on the lower face of the sprocket wheelaround the hub is a ring 27 which is provided with a plurality of spaceddepending lugs 28, each of which carries a plate 29 on its lower end,these plates lying in a plane parallel to the lower face of the sprocketWheel. Each plate is held in position by screws 30 which extend throughthe lug and the sprocket wheel and-also serve to hold the ring 27 inplace on the sprocket wheel. The

plates 29 project beyond the lugs in the direction in which the sprocketwheel is to be driven.

The tool includes a support 31 provided with a fiat disc 32 at one endand on its opposite face the support has a tubular extension 33 forminga recess 34. On the upper end of the extenslon is a ring 35, havingtangential arms 36 corresponding in number to the number of lugs 28.Each of the arms has an under-cut portion, and the arrangement of thearms is such that the tubular extension of the sup ort may be passedover the end of the sha t and by a turning movement of the support thelates 29 on the lugs 28 may be engaged in the under-cut recesses in thearms. The support may thus be mounted on the lugs of the ring 27 carriedby the sprocket wheel 15 and a driving connection between the s rocketwheel and the support is thus established. When the support is to beremoved from the end of the shaft, the support is given a slight turningmovement, freeing the arms from the plates 29, whereupon the support maybe removed from the shaft endwise.

The sup rt has a central depression 37 having a s oping side wall, and aring 38 of yielding material such as felt, is secured to the lower faceof the plate 32. Secured in the support is a threaded stud 39, held inposition in any convenient manner and proecting downwardly into thedepression, as shown in Fi 1.

The abrasive material 40 is in the form of a circular disc of slightlygreater diameter 38. The abrasive disc has a central hole 41 and a1uralitv of slits 42 are cut radially in the isc, as illustrated in Fig.,7. The circle drawn through the outer ends of the slits is ofsubstantially the same diameter as the inner diameter of the ring offelt, and when, the

abrasive disc is placed on the face of the felt the tabs 43 defined bythe slits are bent inwardly so as to lie against the sloping wall of thedepression 37 These tabs are clamped in position against this wall by aclampmg device consisting of a ring 44'having a side wall of the sameslope as the slope of the wall of the depression. A circular plate 45has a channel 46 in its edge in which is received the inner edge of thering 44, and plate 47 secured to the face of the plate 45 slightlyoverlies the portion of the ring 44 received in the channel 46. The ring44 and the plate 45 are thus secured together a ainst detachment but arecapable of relatlve movement. The plate 45 has a central hub 48 threadedon the end of the stud 39 and wing lugs 49 are formed on the lower faceof the plate, these lugs providing means for turning the plate on thestud.

The upper face of the plate 45 is provided with a circular row oflocking teeth 50 and mounted in a-boss 51 in the su port 31 is a pawl52. This pawl has its lower end cut at an angle, as shown at 53, (Fig.5) and it carries a pin 54 entering a notch in the lower end of the boss51, the pin preventing the pawl from-turning. A leaf spring 55 issecured to the upper end of the pawl by means of a portion of the pawlwhich passes through a hole in the spring and is upset to form a rivethead. The spring 55 has a portion which extends inwardly toward the 11per end of the stud 39 and this spring tends to hold the pawl retractedinto the boss 51.

When the tool is to be put in operation, a disc of abrasive paper of theproper size is provided, the central hole is cut in it, and it is thenslit radially, as shown in Fig. 7. The support, with the felt layer inpo- -sition, is then turned up-side-down, the

abrasive disc is put in place, and the tabs are bent downwardly so as tolie against the sloping wall of the depression in the support. The late45 with ring 44 secured to it, is now t readed on the stuu 39 and turneduntil the sloping face of the plate is brought into engagement with thetabs of the abrasive disc. The plate is turned until the face of thering clamps these tabs tightly betweenthe face of the ring and thesloping wall of the depression in the support. The support is now placedon the end of the driving shaft of the machine and turned until the armscarried by the support are engaged by the lugs on the ring carried bythe sprocket. If no locking means for the clamping device were provided,the rotation of the support accompanied by the jarring to which themachine is subjected in use, would cause the clamping device to becomeloose and the abrasive (1150 would sli and stand still so that it woulddo no usefu work and might become injured by the rotation of thesupport. v

With the present tool, however, the placmg of the support with the discin place on the end of the shaft brings the spring 55 into contact withthe end plate 25 on the hollow hub of the sprocket, and the spring isbent downwardly, forcing the pawl 52 into locking engagement with one ofthe teeth on the plate 45, The plate 45 is thus prevented from turning,and the tabs on the abrasive disc are securely clamped throughout theperiod of use of the machine. The spring is shaped so that if, when thesupport is mounted on the end of the hub of the sprocket wheel, the endcap projects downwardly to a greater extent than is necessary to forcethe pawl into locking engagement with the teeth, the spring is simplyflexed to a greater extent without disturbing the engagement of the pawland teeth.

As soon as the support is removed from the end of the shaft, the springis free to return to its normal position, and it retracts the pawl fromengagement with the teeth. The plate 45 may now be turned by the winglugs, releasing the clamping ring from engagement with the tabs of theabrasive disc, and the disc may be removed and another one easily put inposition. It will he observed that the ring 44 and the plate 45 arecapable of'relative movement of rotation, but are otherwise securedtogether against detachment. This permits the clamping ring to be forcedtightly into clamping engagement with the tabs of the abrasive disc,although the ring 44 does not turn. Conserpiently the tabs are notsubjected to a tearing action. At the same time e clamping ring andplate are secured towiii be test.

new tool has been shown arranged e on a machine suitable for treatingthis machine having a carriage proa with wheeis 56 which may be swungnward into engagement with the floor erinit the machine to be moved overthe 1 while the abrasive tool is clear of the tier. The machine is alsoprovided with as usual handie 57, to which the motor E are secured, andthe usual switch for control of the motor- 1s also mounted on he tool isadapted for other a tic-or machine, as will be sanding machine, thecombination n shaft, a support removably mountthe end of the shaft, anabrasive disc sn, means for securing the abradisc in position on thesupport, and carried by the support for locking e "caring means inefi'ective position, the l means engaging the shaft when er so thatthere is no likelihood that the a locking device carried by the supportandengaged by the shaft when the support is mounted thereon, the devicebeing rendered effective thereby to lock the clamping disc in clampingposition.

3. In a sanding machine, the combination of a driven shaft, a supportremovably mounted at theend of the shaft, an abrasive disc on thesupport, a clamping disc for holding the abrasive disc on the sup ort,this clamping disc being provided with ocking teeth, and a lockingdevice carried by the support and engaged by the shaft when the supportis mounted thereon, the device being forced thereby into lockingengagement with the teeth on the clamping disc.

4. In a sanding machine, the combination of a driven shaft, 2. supportremovably mounted at the end of the shaft, an abrasive disc on thesupport, a clamping disc for holding the abrasive disc on the support,this clamping disc being provided with locking teeth, and aspring-pressed pawl carried blyl the support and forced by engagementwit the shaft when the support is placed there on into lockingengagement with the teeth on the clamping disc.

5. In a sanding machine, the combination of a driven shaft, a. supportremovably mounted at the end of the shaft and having a recess into whichthe end of the shaft projects, an abrasive disc carried by the support,a clamping disc for holding the abrasive disc on the support, lockingteeth on the clamping disc, and a spring-pressed pawl mounted on thesupport and forced by the spring into the said recess, this pawl beingso arranged that it is forced out of the recess into engagement with thesaid locking teeth by engagement with the end of the shaft when thesupport is placed thereon.

6. In a sandin machine, the combination of a driven shaft, a supportremovably mounted at the end of the shaft and having a recess into whichthe end of the shaft pro jects, an abrasive disc carried by the support,a clamping disc arranged to clamp the central portion of the abrasivedisc against the support, locking teeth on the clamping disc, a pawl onthe support movable to engage the said locking teeth and therebyefiective to prevent the clamping disc from releasing the abrasive disc,and a spring on the support tending to hold the pawl out of engagementwith the teeth, this spring being engaged by the shaft when the supportis placed thereon, and flexed to force the pawl into engagement with theteeth.

7. In a sanding machine, the combination of a driven shaft, a supportmounted on the shaft, an abrasive element,- means for holding theabrasive element on the support, and cooperating locking elements on thesupport and on the holding means, said elements being brought intolocking engagement only when the support is mounted on the shaft.

In testimony whereof I aflix my signature.

ROBERT A. PONSELLE.

